What is the obvious distinction between AC and DC generators?

• A. DC has a commutator, AC has slip rings
• B. AC has a commutator, DC has slip rings
• C. DC uses slip rings
• D. AC requires no brushes

Answer: (A)

The key idea is how the rotating armature’s electricity is collected to the outside circuit. In a DC generator, a commutator (split ring) is used so that as the coil turns, the connection to the external circuit is swapped in time, keeping the output current in one direction. In an AC generator, slip rings simply connect to the ends of the coil and deliver the instantaneous polarity as the coil rotates, so the output is alternating current. Brushes are typically involved in both, but the commutator in DC machines is what converts the generated AC in the armature into direct current externally, whereas slip rings in AC machines let the AC flow out directly. The other statements mix up how the output is collected and rectified, so they don’t describe the standard distinction.